1. Field of the Invention
The present invention relates to a door lock system configured to lock a rear door to a vehicle body in a vehicle in which an ingress/egress opening is opened and closed by the front and rear, double opening doors.
2. Description of the Related Art
In the vehicle in which the ingress/egress opening is opened and closed by the front and rear, double opening doors, if the rear door can be independently opened earlier than the front door, it is likely that a higher safety standard cannot be obtained because the rear door might be opened before the vehicle pulls up.
Against this background, Japanese Patent Application Publication No. 2002-178756 (hereinafter referred to as Patent Document 1) has proposed an opening/closing system for a vehicle, which prohibits the opening of the rear door while the front door is closed, and which allows the opening of the rear door while the front door is opened. An example of this is shown in FIG. 13.
FIG. 13 is a diagram showing a basic structure of the opening/closing system proposed by Patent Document 1. The illustrated opening/closing system includes: an inner handle 101 provided to the rear door; a lock unit 102 configured to lock the rear door to the vehicle body; a disablement mechanism 103 configured to enable and disable the operation of the inner handle 101 to be transmitted to the lock unit 102; and an actuator (solenoid) 104 configured to switch the disablement mechanism 103 between a transmitting state and a non-transmitting state in response to the opening or closing of the front door. The opening/closing system disables the rear door to be opened while the front door is closed, because the opening and closing of the rear door are locked by the lock unit 102. Even if an occupant manipulates the inner handle 101 while the front door is closed, the manipulation force is not transmitted to the lock unit 102 because of the disablement mechanism 103. Thus, the rear door is kept locked by the lock unit 102, and accordingly remains unable to be opened.
In addition, Japanese Patent Application publication No. 2005-232716 (hereinafter referred to as Patent Document 2) has proposed a door lock system for similar double opening doors in which the states of the disablement mechanism are switched by a mechanical structure as shown in FIG. 14, instead of the actuator.
FIG. 14 shows a basic structure of a door latch system proposed by Patent Document 2. The illustrated door latch system controls the opening and closing of the rear door by: transmitting the operation of an operation lever 201, which is pressed by the front door, to a lock lever 203 of the disablement mechanism via a connecting rod 202; thus making a slide pin 204 work; and thereby switching the states (locked and unlocked states) of the connection between an open lever 206 connected to an inner handle 205 and a ratchet release lever 207.